Enhanced Slag Formation For Copper-Containing Gas Generants

ABSTRACT

Gas generants comprising copper are provided that have improved slagging ability. In certain aspects, the gas generants include a fuel, an oxidizer comprising basic copper nitrate, and a large particle size endothermic slag-forming component, such as aluminum hydroxide (Al(OH)3). The gas generants may be cool burning, e.g., having a maximum flame temperature at combustion (Tc)≤about 1,900K (1,627° C.). The disclosure also provides methods of enhancing slag formation for a gas generant composition that comprises copper. Such methods enhance slag formation during combustion of the gas generant composition by at least 50%.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/799,559, filed on 13 Mar. 2013. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present disclosure relates to enhancing slagging in gas generantscontaining copper by introducing large particle size endothermicslag-forming components.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

Passive inflatable restraint systems are used in a variety ofapplications, such as motor vehicles. Certain types of passiveinflatable restraint systems minimize occupant injuries by using apyrotechnic gas generant to inflate an airbag cushion (e.g., gasinitiators and/or inflators) or to actuate a seatbelt tensioner (e.g.,micro gas generators), for example. Automotive airbag inflatorperformance and safety requirements are continually increasing toenhance passenger safety, while concurrently striving to reducemanufacturing costs.

Thus, increasing functionality of a propellant or a gas generant used inairbag inflators, while improving performance and reducing costs of theentire airbag inflator system has been an ongoing objective in design ofinflatable restraint systems. Gas generant selection involves addressingvarious factors, including meeting current industry performancespecifications, guidelines and standards, generating safe gases oreffluents, durational stability of the materials, and cost-effectivenessin manufacture, among other considerations. Improved gas generatorperformance may be achieved in a variety of ways, many of whichultimately depend on the gas generant formulation to provide the desiredproperties.

Suitable gas generants provide sufficient gas mass flow in a desiredtime interval to achieve a required work impulse for the inflatingdevice. Further, gas generants having lower flame temperatures areadvantageous. In current designs of automotive airbag inflators, asignificant portion of the mass of the inflator is often relegated toheat sink, in combination with filtration systems. This detrimentallyimpacts the weight of the inflator and thus the efficiency of thesystem. Hence, for new advanced inflator designs, it is desirable toreduce or minimize filter and heat sink requirements as much aspossible. As part of these new designs, cool burning gas generantformulations are advantageous because they reduce heat sinkrequirements. Additionally, if filter mass is to be reduced the coolburning gas generant must slag very well, meaning that combustionproducts form a large integral mass that is retained inside thecombustion chamber during combustion and thus does not pass through thefilter into the airbag. Accordingly, enhancing formation of slag invarious gas generants, especially in cool burning gas generants would behighly desirable to produce lighter, more efficient inflator designs.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present disclosure pertains to gas generant compositions comprisingcopper having improved slagging properties. For example, in certainvariations, the present disclosure provides a gas generant compositioncomprising a fuel, an oxidizer comprising basic copper nitrate, and anendothermic slag-forming component having an average particle sizediameter of greater than or equal to about 150 μm. The gas generantcomposition has a maximum flame temperature at combustion (T_(c)) ofless than or equal to about 1,900K (1,627° C.).

In another variation, the present disclosure provides a gas generantcomposition comprising a fuel, at least one oxidizer comprising basiccopper nitrate, and an endothermic slag-forming component comprisingaluminum hydroxide having an average particle size diameter of greaterthan or equal to about 150 μm. The gas generant composition has amaximum flame temperature at combustion (T_(c)) of less than or equal toabout 1,900K (1,627° C.). In certain aspects, such a gas generantcomposition may have a maximum flame temperature at combustion (T_(c))of greater than or equal to about 1,350K (1,077° C.) to less than orequal to about 1,450K (1,177° C.).

In yet another variation, the present disclosure provides a method ofenhancing slag formation for a gas generant composition. The method maycomprise introducing an endothermic slag-forming component having anaverage particle diameter size of greater than or equal to about 150 μmto a gas generant composition comprising a fuel and an oxidizercomprising basic copper nitrate. The introducing of the endothermicslag-forming component enhances slag formation during combustion of thegas generant composition by at least 50%.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a partial cross-sectional view of an exemplary passenger-sideairbag module including an inflator for an inflatable airbag restraintdevice.

FIG. 2 shows an acceptable particle size distribution for a largeparticle size endothermic slag-forming aluminum hydroxide for use inaccordance with various aspects of the present disclosure.

FIG. 3 shows a macroscopic photograph of a slag formed from aconventional gas generant.

FIG. 4 shows a microscopic photograph of the slag in FIG. 3 formed fromthe comparative example of a conventional gas generant. Magnification isat 50 times.

FIG. 5 shows a macroscopic photograph of a slag formed from a gasgenerant prepared in accordance with certain aspects of the presentdisclosure.

FIG. 6 shows a microscopic photograph of the slag in FIG. 5 formed fromthe gas generant prepared in accordance with certain aspects of thepresent disclosure. Magnification is at 50 times.

FIG. 7 shows a photograph of a slag formed from a comparativeconventional gas generant in a post-fire inflator combustion chamber.

FIG. 8 shows a photograph of slag formed from the gas generant preparedin accordance with certain aspects of the present disclosure in apost-fire inflator combustion chamber.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Although theterms first, second, third, etc. may be used herein to describe variouscomponents, elements, regions, layers and/or sections, these components,elements, regions, layers and/or sections should not be limited by theseterms. These terms may be only used to distinguish one element,component, region, layer or section from another region, layer orsection. Terms such as “primary,” “secondary,” “first,” “second,” or andother numerical terms when used herein do not imply a sequence or orderunless clearly indicated by the context. Thus, a first or primarycomponent, element, region, layer or section discussed below could betermed a secondary component, element, region, layer or section withoutdeparting from the teachings of the example embodiments.

Throughout this disclosure, the numerical values represent approximatemeasures or limits to ranges to encompass minor deviations from thegiven values and embodiments having about the value mentioned as well asthose having exactly the value mentioned. Other than in the workingexamples provided at the end of the detailed description, all numericalvalues of parameters (e.g., of quantities or conditions) in thisspecification, including the appended claims, are to be understood asbeing modified in all instances by the term “about” whether or not“about” actually appears before the numerical value. “About” indicatesthat the stated numerical value allows some slight imprecision (withsome approach to exactness in the value; approximately or reasonablyclose to the value; nearly). If the imprecision provided by “about” isnot otherwise understood in the art with this ordinary meaning, then“about” as used herein indicates at least variations that may arise fromordinary methods of measuring and using such parameters.

As referred to herein, ranges are, unless specified otherwise, inclusiveof endpoints and include disclosure of all distinct values and furtherdivided ranges within the entire range. Thus, for example, a range of“from A to B” or “from about A to about B” is inclusive of A and of B.Disclosure of values and ranges of values for specific parameters (suchas weight percentages, temperatures, molecular weights, etc.) are notexclusive of other values and ranges of values useful herein. It isenvisioned that two or more specific exemplified values for a givenparameter may define endpoints for a range of values that may be claimedfor the parameter. For example, if Parameter X is exemplified herein tohave value A and also exemplified to have value Z, it is envisioned thatParameter X may have a range of values from about A to about Z.Similarly, it is envisioned that disclosure of two or more ranges ofvalues for a parameter (whether such ranges are nested, overlapping ordistinct) subsume all possible combination of ranges for the value thatmight be claimed using endpoints of the disclosed ranges. For example,if Parameter X is exemplified herein to have values in the range of1-10, or 2-9, or 3-8, it is also envisioned that Parameter X may haveother ranges of values including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3,3-10, and 3-9. Example embodiments will now be described more fully withreference to the accompanying drawings.

The present disclosure is drawn to gas generant compositions and methodsfor enhancing slag formation in such gas generant compositions. Gasgenerants, also known as propellants, gas-generating materials, andpyrotechnic materials are used in inflators of airbag modules, such as asimplified exemplary airbag module 30 comprising a passenger compartmentinflator assembly 32 and a covered compartment 34 to store an airbag 36of FIG. 1. A gas generant material 50 burns to produce the majority ofgas products that are directed to the airbag 36 to provide inflation.Such devices often use a squib or initiator 40 which is electricallyignited when rapid deceleration and/or collision is sensed. Thedischarge from the squib 40 usually ignites an igniter material 42 thatburns rapidly and exothermically, in turn, igniting a gas generantmaterial 50.

The gas generant 50 can be in the form of a solid grain, a pellet, atablet, or the like. “Slag” or “clinker” is another name for solidcombustion products formed during combustion of the gas generantmaterial. The composition of slag is mainly metals and metal oxides.Ideally, the slag will maintain the original shape of the gas generant(e.g., grain, pellet, or tablet) and be large and easily filtered. Thisis particularly important when the inflator design includes a reducedmass filtration system for the purpose of reducing the inflator size andweight such as can be used with cool burning gas generant formulations.As shown in FIG. 1, an exemplary conventional filter system 52 isprovided between gas generant 50 and airbag 36. The quality and toxicityof the components of the gas produced by the gas generant 50, alsoreferred to as effluent, are important because occupants of the vehicleare potentially exposed to these compounds. It is desirable to minimizethe concentration of potentially harmful compounds in the effluent.

Various different gas generant compositions (e.g., 50) are used invehicular occupant inflatable restraint systems. Gas generant materialselection involves various factors, including meeting current industryperformance specifications, guidelines and standards, generating safegases or effluents, handling safety of the gas generant materials,durational stability of the materials, and cost-effectiveness inmanufacture, among other considerations. It is preferred that the gasgenerant compositions are safe during handling, storage, and disposal,and preferably are azide-free.

In various aspects, the gas generant typically includes at least onefuel component and at least one oxidizer component, and may includeother minor ingredients, that once ignited combust rapidly to formgaseous reaction products (e.g., CO₂, H₂O, and N₂). One or more fuelcompounds undergo rapid combustion to form heat and gaseous products;e.g., the gas generant burns to create heated inflation gas for aninflatable restraint device or to actuate a piston. The gas-generatingcomposition also includes one or more oxidizing components, where theoxidizing component reacts with the fuel component in order to generatethe gas product.

Improved gas generator performance in an inflatable restraint system maybe achieved in a variety of ways, many of which ultimately depend on thegas generant formulation to provide the desired properties. Ideally, agas generant provides sufficient gas mass flow in a desired timeinterval to achieve the required work impulse for an inflating device(e.g., airbag) within the inflatable restraint system. Although atemperature of gas generated by the gas generant influences the amountof work gases can do, high gas temperatures may be undesirable becauseburns and related thermal damage can result. In addition, high gastemperatures can also potentially lead to an excessive reliance orsensitivity of the gas to heat transfer and excessively rapid deflationprofiles, which can likewise be undesirable. For example, a cool burninggas generant having combustion flame temperatures of less thanapproximately 1,900K (1,627° C.) has been shown to enable inflatordevices with reduced filtration, which operate in a manner that providesadequate restraint and protection, without the risk of burns or injuryto an automobile occupant in the event of a crash. Thus, minimizingflame temperature is advantageous. In certain aspects of the presenttechnology, a high flame temperature may be considered anything inexcess of about 1,900K (1,627° C.) at combustion.

In order to mitigate the effects of high flame temperatures, inconventional inflatable restraint system gas generators, a significantportion of mass of an inflator is often relegated to heat sink incombination with filtration. This impacts the efficiency of the systemand, most significantly, the weight of the inflator. Consequently, incertain aspects, it is desirable to provide a gas generant formulationfor an inflatable restraint system that can achieve a high gas output ata high mass flow rate at relatively low flame temperatures. Furthermore,it would be desirable to employ a gas generant formulation that hasenhanced slag forming abilities, so that attendant filter components canbe reduced within the inflator component to further improve efficiency.Other important variables in inflator gas generant design includeimproving gas generant performance with respect to gas yield, relativequickness (as determined by observed burning rate), and cost.

Advanced inflator design concepts incorporate reduced filter and heatsink mass, as well as reduced containment wall thickness coupled withfiberglass/resin reinforcement to achieve significant weight reductionin the inflator. Use of cool burning gas generant formulations reducesheat sink requirements. Additionally, because filter mass is reduced, itis desirable to have a cool burning gas generant that slags very well.By “slagging” it is meant that certain solid combustion productsgenerated during burning of the gas generant form a large integral solidmass that is retained inside the combustion chamber during combustion,rather than passing through the filter into the airbag. Traditionalslagging agents have been used to achieve this effect. A slagging agentis a compound or material, usually inert to combustion, that melts atcombustion temperatures and agglomerates or collects all of the solidcombustion products together. Examples of conventional slagging agentsare silicon dioxide, aluminum oxide, glass and other metal oxides thatmelt at or near the combustion flame temperature.

In various aspects, the present disclosure provides a relatively coolburning gas generant composition that comprises a fuel and an oxidizer.In certain embodiments, the gas generant composition comprises a fueland an oxidizer comprising copper. In further embodiments, the gasgenerant comprises a fuel and an oxidizer comprising basic coppernitrate. In certain aspects, the gas generant composition has a maximumflame temperature at combustion (T_(c)) of less than or equal to about1,900K (1,627° C.) and in certain other aspects, optionally less than orequal to about 1,700K (1,427° C.). In accordance with various aspects ofthe present teachings, a large particle size endothermic slag-formingcomponent is introduced to the gas generant composition to significantlyenhance formation of slag when such a gas generant component iscombusted. The endothermic slag-forming component particles preferablyhave an average particle size diameter of greater than or equal to about150 μm. In certain aspects, the endothermic slag-forming component has adecomposition temperature in a range of greater than or equal to about180° C. to less than or equal to about 450° C., meaning that thecompound decomposes endothermically within this temperature range, forexample, by releasing water or carbon dioxide.

In certain preferred variations, the endothermic slag-forming componentcomprises a large particle size aluminum hydroxide (Al(OH)₃). However,in alternative variations, the following compounds may be employed asendothermic slag-forming components in gas generant compositionscomprising copper: hydromagnesite (Mg₅(CO₃)₄(OH)₂.4H₂O), Dawsonite(NaAl(OH)₂CO₃), magnesium hydroxide (Mg(OH)₂), magnesium carbonatesubhydrate (MgOCO₂.H₂O_((0.3))), Bohemite (AlO(OH)), calcium hydroxide(Ca(OH)₂), and combinations thereof. Each of these compounds decomposesendothermically within the desired temperature range of greater than orequal to about 180° C. to less than or equal to about 450° C., as setforth in Table 1 below.

TABLE 1 Decomposition Compound Chemical Formula Temperature ° C.Aluminum Hydroxide Al(OH)₃ 180-200 Hydromagnesite Mg₅(CO₃)₄(OH)₂•4H₂0220-240 Dawsonite NaAl(OH)₂CO₃ 240-260 Magnesium Hydroxide Mg(OH)₂300-320 Magnesium Carbonate MgOCO₂•H₂O_((0.3)) 340-350 SubhydrateBohemite AlO(OH) 340-350 Calcium Hydroxide Ca(OH)₂ 430-450

The endothermic slag-forming component has specific particle sizerequirements to provide certain benefits associated with the inventivetechnology. In certain embodiments, the endothermic slag-formingcomponent comprises a large particle size aluminum hydroxide (Al(OH)₃).The inventive technology contemplates use of aluminum hydroxide havingvery specific particle size properties, which greatly improves slagformation while also cooling a copper-containing gas generant flametemperature (e.g., a maximum combustion flame temperature lowered toabout 1,350K (1,077° C.)-1,450K (1,177° C.).

In certain variations, endothermic slag-forming component particles(e.g., aluminum hydroxide particles) have a large particle size. By“large particle size,” it is meant that an average particle sizediameter of the endothermic slag-forming component particles (e.g.,aluminum hydroxide particles) is greater than or equal to 150micrometers (μm), optionally greater than or equal to about 175 μm,optionally greater than or equal to about 200 μm, optionally greaterthan or equal to about 225 μm, optionally greater than or equal to about250 μm, optionally greater than or equal to about 275 μm, and in certainvariations greater than or equal to about 300 μm. The particle sizedistribution for the endothermic slag-forming component particles mayhave a 10% value of greater than or equal to about 100 μm (micrometers);optionally greater than or equal to about 115 μm. In certain variations,the particle size distribution has an average (50%) particle size ofgreater than or equal to about 150 μm, while also having a 10% value ofgreater than or equal to about 100 μm. Furthermore, particle sizedistributions of endothermic slag-forming component particles with 90%values of 200 to 300 μm also provide desired advantages associated withcertain aspects of the present teachings. One suitable example of alarge particle size aluminum hydroxide has a particle size distribution10% value of about 115 μm, a 50% value of about 158 μm (thus an averageparticle size diameter of 158 μm), and a 90% value of about 288 μm. Anexample of such an acceptable particle size for an aluminum hydroxidethat fulfills the requirements for use in accordance with the presenttechnology is shown in FIG. 2, which has an average particle sizediameter as described just above. Thus, relatively large particlesprovide the desirable slagging ability to the gas generant compositionscomprising copper.

In accordance with various aspects of the present disclosure, gasgenerants are provided that have desirable compositions that result insuperior performance characteristics in an inflatable restraint device,while reducing overall cost of gas generant and inflator assemblyproduction. Thus, in accordance with various aspects of the presentteachings, an improved cool burning gas generant composition is providedthat has a maximum combustion temperature (T_(c)) (also expressed asmaximum combustion flame temperature) of less than or equal to about1,900K (1,627° C.). In certain variations, the maximum combustiontemperature is less than or equal to about 1,800K (1,527° C.),optionally less than or equal to about 1,700K (1,427° C.), optionallyless than or equal to about 1,600K (1,327° C.) and in certainvariations, less than or equal to about 1,500K (1,227° C.). In variousembodiments, it is preferred that the flame temperature duringcombustion for a cool burning gas generant is greater than or equal toabout 1,300K (1,027° C.) to less than or equal to about 1,700K (1,427°C.).

Additionally, in various aspects, the gas generant may have a high massdensity in various embodiments. For example, in certain embodiments, thegas generant has a theoretical mass density of greater than or equal toabout 2 g/cm³, optionally greater than or equal to about 2.25 g/cm³,optionally greater than or equal to about 2.5 g/cm³, and in certainvariations, optionally greater than or equal to about 2.75 g/cm³.

Further, in accordance with the present disclosure, the gravimetric gasyield of the gas generant is relatively high. For example, in certainembodiments, the gravimetric gas yield is greater than or equal to about1.8 moles/100 grams of gas generant. In other embodiments, thegravimetric gas yield is greater than or equal to about 1.9 moles/100 gof gas generant, optionally greater than or equal to about 2.0 moles/100g of gas generant, optionally greater than or equal to about 2.1moles/100 g of gas generant, optionally greater than or equal to about2.2 moles/100 g of gas generant, optionally greater than or equal toabout 2.3 moles/100 g of gas generant, optionally greater than or equalto about 2.4 moles/100 g of gas generant, optionally greater than orequal to about 2.5 moles/100 g of gas generant, and in certainvariations, optionally greater than or equal to about 2.6 moles/100 g ofgas generant. The product of gravimetric gas yield and density is avolumetric gas yield.

In other aspects, the volumetric gas yield of a gas generant accordingto certain variations of the present disclosure is optionally greaterthan or equal to about 5.0 moles/100 cm³ of gas generant. In otherembodiments, the volumetric gas yield is greater than or equal to about5.1 moles/100 cm³ of gas generant, optionally greater than or equal toabout 5.2 moles/100 cm³ of gas generant, optionally greater than orequal to about 5.3 moles/100 cm³ of gas generant, optionally greaterthan or equal to about 5.4 moles/100 cm³ of gas generant, optionallygreater than or equal to about 5.5 moles/100 cm³ of gas generant, and incertain variations, optionally greater than or equal to about 5.6moles/100 cm³ of gas generant.

Thus, the present technology provides enhanced slag formation for coolburning gas generants. Thus, in certain aspects, the disclosure providesa gas generant composition comprising copper having good slag formingcapabilities. For example, the gas generant composition may comprise atleast one fuel, at least one oxidizer comprising copper, a largeparticle size endothermic slag-forming component, and optionally minoramounts of conventional gas generant additives. Materials are generallycategorized as gas generant fuels due to their relatively low burnrates, and are often combined with one or more oxidizers in order toobtain desired burn rates and gas production. As appreciated by those ofskill in the art, such a fuel component may be combined with additionalcomponents in the gas generant, such as co-fuels or oxidizers. Mostfuels known in the art can be used with the present technology and aregenerally selected to impart certain desirable characteristics to thegas generant formulation, such as gas yield, burning rate, thermalstability, and low cost. These fuels can be organic compounds containingtwo or more of the elements: carbon (C), hydrogen (H), nitrogen (N), andoxygen (O). The fuels can also include transition metal salts andtransition metal nitrate complexes. In certain variations, preferredtransition metals are copper and/or cobalt. In accordance with certainaspects of the present teachings, a fuel is selected for the inventivegas generant compositions so that when combusted with certain oxidizerscomprising copper, such as basic copper nitrate, a resulting maximumcombustion flame temperature (T_(c)) falls within a range of greaterthan or equal to about 1,400K (1,127° C.) to less than or equal to1,900K (1,627° C.).

Examples of fuels useful for gas generants according to the presentteachings are selected from the group consisting of guanidine nitrate,copper bis guanylurea dinitrate, hexamine cobalt (III) nitrate, copperdiammine bitetrazole, and combinations thereof. Fuels may be used singlyor in combination with other co-fuels to impart the desired combustioncharacteristics. A suitable gas generant composition optionally includesgreater than or equal to about 25% to less than or equal to about 70% byweight; optionally greater than or equal to about 30% to less than orequal to about 55% of all fuel components in the total gas generantcomposition.

The gas generant formulations according to various aspects of thepresent teachings include an oxidizer comprising copper as a mainoxidizer. A particularly suitable oxidizer for the gas generantcompositions of the present disclosure is basic copper nitrate. Basiccopper nitrate has a high oxygen-to-metal ratio and good slag formingcapabilities upon burn. By way of example, a suitable gas generantcomposition optionally includes greater than or equal to about 25% toless than or equal to about 75% by weight of the oxidizer, such as basiccopper nitrate; optionally greater than or equal to about 30% to lessthan or equal to about 60% by weight of the oxidizer, such as basiccopper nitrate, in the total gas generant composition.

The gas generant may include combinations of oxidizers, such that theoxidizer comprising copper may be nominally considered to be a primaryoxidizer, so that additional oxidizers are referred to as a secondaryoxidizer, and the like. In certain variations, the gas generantcomposition may comprise an oxidizer comprising a perchlorate-containingcompound (a compound including a perchlorate group (ClO₄ ⁻)). In certainvariations, the gas generant compositions may be substantially free ofperchlorate-containing compounds. However, if suchperchlorate-containing compounds are present in relatively smallamounts, alkali, alkaline earth, and ammonium perchlorates arecontemplated for use in the gas generant compositions. Particularlysuitable perchlorate oxidizers include alkali metal perchlorates andammonium perchlorates, such as ammonium perchlorate (NH₄ClO₄), sodiumperchlorate (NaClO₄), potassium perchlorate (KClO₄), lithium perchlorate(LiClO₄), magnesium perchlorate (Mg(ClO₄)₂), and combinations thereof.If perchlorate oxidizers are present in the gas generant, it ispreferably at less than about 3% by weight of the total gas generantcomposition. By way of example, a perchlorate containing oxidizer ispresent in certain embodiments at about 0.1% to about 3% by weight; andoptionally about 0.5 to about 2% by weight of the gas generant.

As discussed above, in accordance with the present technology, the gasgenerant composition further comprises an endothermic slag-formingcomponent having a large particle size. In certain variations, theendothermic slag-forming component is selected from the group consistingof: aluminum hydroxide, hydromagnesite, Dawsonite, magnesium hydroxide,magnesium carbonate subhydrate, Bohemite, calcium hydroxide, andcombinations thereof. In various aspects, the endothermic slag-formingcomponent may be present at greater than or equal to about 5% by weightto less than or equal to about 20% by weight of a total gas generantcomposition; optionally at greater than or equal to about 7% to lessthan or equal to about 18%; optionally at greater than or equal to about8% to less than or equal to about 16%; and in certain variations,greater than or equal to about 10% to less than or equal to about 15% byweight of a total gas generant composition.

If desired, a gas generant composition may optionally include additionalcomponents known to those of skill in the art. Such additives typicallyfunction to improve the handling or other material characteristics ofthe slag which remains after combustion of the gas generant material;and improve ability to handle or process pyrotechnic raw materials. Byway of non-limiting example, additional ingredients for the gas generantcomposition may be selected from the group consisting of: flow aids,pressing aids, metal oxides, and combinations thereof. If minoringredients are included in the gas generant, they may be cumulativelypresent at less than or equal to about 4% by weight of the total gasgenerant composition. By way of example, such an additive may beselected from the group consisting of: flow aids, press aids, metaloxides, and combinations thereof is present in a gas generantcomposition, in certain variations each respective additive is presentat greater than or equal to 0% to less than or equal to about 3% byweight; optionally greater than or equal to about 0.1% to less than orequal to about 2% by weight, and in certain variations, optionallygreater than or equal to about 0.5% to less than or equal to about 1% byweight of the gas generant, so that the total amount of additives isless than or equal to about 4%.

Press aids used during compression processing, include lubricants and/orrelease agents, such as graphite, calcium stearate, magnesium stearate,molybdenum disulfide, tungsten disulfide, graphitic boron nitride, maybe optionally included in the gas generant compositions, by way ofnon-limiting example. Conventional flow aids may also be employed, suchas high surface area fumed silica.

The gas generant compositions may optionally include a metal oxide thatserves as a viscosity modifying compound or an additional slag formingagent (in addition to the endothermic slag-forming component describedabove). Suitable metal oxides may include silicon dioxide, cerium oxide,ferric oxide, titanium oxide, zirconium oxide, bismuth oxide, molybdenumoxide, lanthanum oxide and the like.

A gas generant composition according to certain aspects of the presentdisclosure comprises a fuel component, an oxidizer comprising basiccopper nitrate, and an endothermic slag-forming component having anaverage particle size diameter of greater than or equal to about 150Such a gas generant composition preferably has a maximum flametemperature at combustion (T_(c)) of less than or equal to about 1,900K(1,627° C.). The gas generant composition may further comprise aco-oxidizer, such as a perchlorate-based compound. In certainvariations, a gas generant composition comprises greater than or equalto about 5% to less than or equal to about 70% by weight of the gasgenerant composition, an oxidizer comprising basic copper nitratepresent at greater than or equal to about 25% to less than or equal toabout 75% by weight of the gas generant composition, a co-oxidizercomprising a perchlorate-based compound present at greater than or equalto 0% to less than or equal to about 3% by weight of the gas generantcomposition, and an endothermic slag-forming component having an averageparticle size diameter of greater than or equal to about 150 μm presentat greater than or equal to about 5% to less than or equal to about 20%by weight of the gas generant composition. In certain variations, thegas generant composition may further comprise an additive selected fromthe group consisting of: flow aids, press aids, metal oxides, andcombinations thereof, wherein a cumulative amount of the additive(s) isgreater than or equal to 0% to less than or equal to about 4% of the gasgenerant composition. The inventive gas generant formulations are coolburning and show a significant improvement in slagging, as will bediscussed in greater detail below.

In other variations, a gas generant composition comprises a fuelselected from the group consisting of: guanidine nitrate, copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diamminebitetrazole, and combinations thereof, present at greater than or equalto about 25% to less than or equal to about 70% by weight. The gasgenerant also comprises an oxidizer comprising basic copper nitratepresent at greater than or equal to about 25% to less than or equal toabout 75% by weight of the gas generant composition. In certain aspects,the gas generant composition may further comprise a co-oxidizer, such asa perchlorate-based compound present at greater than or equal to 0% toless than or equal to about 3%. Further, the gas generant includes anendothermic slag-forming component having an average particle sizediameter of greater than or equal to about 150 μm selected from thegroup consisting of: aluminum hydroxide, hydromagnesite, Dawsonite,magnesium hydroxide, magnesium carbonate subhydrate, Bohemite, calciumhydroxide, and combinations thereof, which is present at greater than orequal to about 5% to less than or equal to about 20% by weight of thegas generant composition. In certain variations, the gas generantcomposition comprises an additive selected from the group consisting of:flow aids, press aids, metal oxides, and combinations thereof, where acumulative amount of the additive(s) is greater than or equal to 0% toless than or equal to about 4% of the gas generant composition. Such agas generant composition preferably has a maximum flame temperature atcombustion (T_(c)) of less than or equal to about 1,900K (1,627° C.) andcan achieve a resultant flame temperature of between about 1,350K(1,077° C.) to 1,450K (1,177° C.).

In certain other variations, a gas generant composition comprises a fuelcomprising guanidine nitrate present at greater than or equal to about25% to less than or equal to about 70% by weight. The gas generant alsoincludes an oxidizer comprising basic copper nitrate at greater than orequal to about 25% to less than or equal to about 75% by weight of thegas generant composition. In certain variations, a co-oxidizer isoptionally present, for example a co-oxidizer that comprises aperchlorate-based compound present at greater than or equal to 0% toless than or equal to about 3% by weight of the gas generantcomposition. Further, the gas generant includes an endothermicslag-forming component comprising aluminum hydroxide (Al(OH)₃) having anaverage particle size diameter of greater than or equal to about 150 μmpresent at greater than or equal to about 5% to less than or equal toabout 20% by weight of the gas generant composition. In certainvariations, such a gas generant composition optionally comprises anadditive selected from the group consisting of: flow aids, press aids,metal oxides, and combinations thereof, where a cumulative amount of theadditive(s) is greater than or equal to 0% to less than or equal toabout 4% of the gas generant composition. Such a gas generantcomposition preferably has a maximum flame temperature at combustion(T_(c)) of less than or equal to about 1,900K (1,627° C.) and canachieve a resultant flame temperature of between about 1,350K (1,077°C.) to 1,450K (1,177° C.).

In yet other variations, a gas generant composition according to certainaspects of the present disclosure consists essentially of a fuelcomponent, an oxidizer comprising basic copper nitrate, and anendothermic slag-forming component having an average particle sizediameter of greater than or equal to about 150 μm. Such a gas generantcomposition preferably has a maximum flame temperature at combustion(T_(c)) of less than or equal to about 1,900K (1,627° C.). In certainvariations, a gas generant composition consists essentially of greaterthan or equal to about 25% of a fuel to less than or equal to about 70%by weight of the gas generant composition, an oxidizer comprising basiccopper nitrate present at greater than or equal to about 25% to lessthan or equal to about 75% by weight of the gas generant composition, aco-oxidizer comprising a perchlorate-based compound present at greaterthan or equal to 0% to less than or equal to about 3% by weight of thegas generant composition, and an endothermic slag-forming componenthaving an average particle size diameter of greater than or equal toabout 150 μm present at greater than or equal to about 5% to less thanor equal to about 20% by weight of the gas generant composition and anoptional additive selected from the group consisting of: flow aids,press aids, metal oxides, and combinations thereof, wherein a cumulativeamount of the additive(s) is greater than or equal to 0% to less than orequal to about 4% of the gas generant composition.

In other variations, a gas generant composition consists essentially ofa fuel selected from the group consisting of: guanidine nitrate, copperbis guanylurea dinitrate, hexamine cobalt (III) nitrate, copper diamminebitetrazole, and combinations thereof; an oxidizer comprising basiccopper nitrate; a co-oxidizer comprising a perchlorate-based compoundpresent at greater than or equal to 0% to less than or equal to about 3%by weight of the gas generant composition; an endothermic slag-formingcomponent having an average particle size diameter of greater than orequal to about 150 μm selected from the group consisting of: aluminumhydroxide, hydromagnesite, Dawsonite, magnesium hydroxide, magnesiumcarbonate subhydrate, Bohemite, calcium hydroxide, and combinationsthereof; and an optional additive selected from the group consisting of:flow aids, press aids, metal oxides, and combinations thereof. Such agas generant composition preferably has a maximum flame temperature atcombustion (T_(c)) of less than or equal to about 1,900K (1,627° C.) andcan achieve a resultant flame temperature of between about 1,350K(1,077° C.) to 1,450K (1,177° C.).

In yet other variations, a gas generant composition consists essentiallyof a fuel selected from the group consisting of: guanidine nitrate,copper bis guanylurea dinitrate, hexamine cobalt (III) nitrate, copperdiammine bitetrazole, and combinations thereof, present at greater thanor equal to about 25% to less than or equal to about 70% by weight; anoxidizer comprising basic copper nitrate present at greater than orequal to about 25% to less than or equal to about 75% by weight of thegas generant composition; a co-oxidizer comprising a perchlorate-basedcompound present at greater than or equal to 0% to less than or equal toabout 3% by weight of the gas generant composition; an endothermicslag-forming component having an average particle size diameter ofgreater than or equal to about 150 μm selected from the group consistingof: aluminum hydroxide, hydromagnesite, Dawsonite, magnesium hydroxide,magnesium carbonate subhydrate, Bohemite, calcium hydroxide, andcombinations thereof, which is present at greater than or equal to about5% to less than or equal to about 20% by weight of the gas generantcomposition; and an optional additive selected from the group consistingof: flow aids, press aids, metal oxides, and combinations thereof, wherea cumulative amount of the additive(s) is greater than or equal to 0% toless than or equal to about 4% of the gas generant composition. Such agas generant composition preferably has a maximum flame temperature atcombustion (T_(c)) of less than or equal to about 1,900K (1,627° C.) andcan achieve a resultant flame temperature of between about 1,350K(1,077° C.) to 1,450K (1,177° C.).

In certain other variations, a gas generant composition consistsessentially of a fuel comprising guanidine nitrate, an oxidizercomprising basic copper nitrate, a co-oxidizer comprising aperchlorate-based compound, an endothermic slag-forming componentcomprising aluminum hydroxide (Al(OH)₃) having an average particle sizediameter of greater than or equal to about 150 μm, and an optionaladditive selected from the group consisting of: flow aids, press aids,metal oxides, and combinations thereof. Such a gas generant compositionpreferably has a maximum flame temperature at combustion (T_(c)) of lessthan or equal to about 1,900K (1,627° C.).

In other embodiments, a gas generant composition consists essentially ofa fuel comprising guanidine nitrate, an oxidizer comprising basic coppernitrate, an endothermic slag-forming component comprising aluminumhydroxide (Al(OH)₃) having an average particle size diameter of greaterthan or equal to about 150 μm, and an optional additive selected fromthe group consisting of: flow aids, press aids, metal oxides, andcombinations thereof. In certain variations, the fuel comprisingguanidine nitrate is present at greater than or equal to about 25% toless than or equal to about 70% by weight. The oxidizer comprising basiccopper nitrate can be present at greater than or equal to about 25% toless than or equal to about 75% by weight of the gas generantcomposition. Further, the aluminum hydroxide is present at greater thanor equal to about 5% to less than or equal to about 20% by weight of thegas generant composition. The additive or additives may be present in acumulative total amount of greater than or equal to 0% to less than orequal to about 4% of the gas generant composition. Such a gas generantcomposition preferably has a maximum flame temperature at combustion(T_(c)) of less than or equal to about 1,900K (1,627° C.).

Example 1

Experiments are performed to determine the effect of aluminum hydroxideparticle size on slag formation in a representative gas generantformulation. Comparative Example 1 has a conventional smaller size ofaluminum hydroxide particle, while Example 2 is prepared in accordancewith certain aspects of the present teachings. The ingredients for thegas generant and their properties for both Comparative Example 1 andExample 2 are given in Table 2.

TABLE 2 Ingredient Comparative Example 1 Example 2 % basic coppernitrate 38.68 38.68 % guanidine nitrate 17.27 17.27 % copper bisguanylurea dinitrate 28.84 28.84 % glass fibers 0.88 0.88 % aluminumhydroxide 14.32 14.32 10% Particle  54 μm 115 μm Size Distribution (PSD)Aluminum Hydroxide 50% PSD Aluminum Hydroxide  87 μm 158 μm 90% PSDAluminum Hydroxide 152 μm 228 μm Flame Temperature K 1,400 1,400

The respective formulations are prepared and pressed into 0.5″ diameterby 0.43″ cylinders at 12,000 lbs force. These samples are prepared byspray drying a formulation containing guanidine nitrate, basic coppernitrate, copper bis guanylurea dinitrate, and glass fibers. The spraydried formulation is then dry blended with the different particle sizealuminum hydroxide and pressed into the 0.5×0.43″ diameter cylinder.Cylinders are then burned in a 1 liter enclosed bomb under 3,000 psinitrogen. Slag from Comparative Example 1, although in the shape of theoriginal cylinder, had very low density and fell apart to the touch.Slag from Example 2 maintains the shape of the original cylinder, hasgood density, and does not fall apart when handling. Macroscopic andmicroscope pictures of slag from Comparative Example 1 and Example 2 areshown in FIGS. 3-4 (Comparative Example 1) and 5-6 (Example 2),respectively. Magnification is 50× in the microscopic pictures in FIGS.4 and 6.

The combustion slag in FIG. 4 shows spheres of molten copper and spheresof aluminum oxide loosely associated with each other, which results invery weak slag that falls apart and can breach the filter and enter theairbag during deployment. The combustion slag in FIG. 6 shows largespheres of aluminum oxide coated and surrounded by a molten coppermatrix. This results in slag with greater structural strength thatresists coming apart and breaching the filter during combustion. Whilenot limiting the present disclosure to any particular theory, it isbelieved that a larger particle size aluminum hydroxide stays coolerlonger during combustion, for example, due to reduced surface area andslower heat transfer, as compared to smaller particles of aluminumhydroxide. The cooler surfaces thus can provide a site for molten copperto condense on as it is formed resulting in an improved slaggingproduct.

Example 2

Gas generants of Comparative Example 1 and Example 2 described in thecontext of Example 1 are also pressed into 0.25″ diameter x 0.060″tablets, loaded into a driver side automotive airbag inflator, anddeployed into a 60 liter tank. After deployment, the tank is washed downand the wash water collected. The insoluble particulate is captured on afilter and weighed after drying. Any soluble particulate is precipitatedby evaporation of the wash water and weighed. The total particulateescaping the combustion filter is determined by adding the weights ofthe soluble and insoluble particulate found in the tank. This value iscalled the “tank wash value.”

Tank wash values for gas generants from Comparative Example 1 andExample 2 are given in Table 3.

TABLE 3 Comparative Example 1 Example 2 Tank Wash (g) 2.5-3.9 0.5-0.9

As shown in Table 3, the amount of particulate escaping the filter isgreatly reduced when using the inventive gas generant from Example 2(having a large particle size aluminum hydroxide), as compared to gasgenerant from Comparative Example 1 (having a small particle sizealuminum hydroxide). For example, a minimum reduction of tank wash value(and thus enhancement of slag formation) is 64%, while a maximumreduction of tank wash value is 87%. An average reduction in tank washvalue is 78%. Thus, by introducing large particle size aluminumhydroxide in accordance with certain aspects of the present disclosure,a significant enhancement in slag formation occurs for gas generantcompositions.

The inflator combustion chambers from these tests are machined open andthe combustion slag is visually examined. Pictures of the post-firecombustion slags from Comparative Example 1 and Example 2 are shown inFIGS. 7 and 8. As the pictures show, the slag in FIG. 7 from gasgenerant in Comparative Example 1 is very weak, most of it ending up asa loose powder in the combustion chamber. The slag in FIG. 8 from aninventive gas generant in Example 2 is quite intact, maintaining theshape of the original tablets with very little loose powder present.

Thus, in certain aspects, the present disclosure provides a method ofenhancing slag formation for a gas generant composition. The methodcomprises introducing an endothermic slag-forming component having anaverage particle diameter size of greater than or equal to about 150 μmto a gas generant composition that comprises copper. In certainembodiments, the gas generant comprises a fuel and an oxidizercomprising copper. In further embodiments, the gas generant comprises afuel and an oxidizer comprising basic copper nitrate. Any of the gasgenerant compositions described previously above are contemplated.Similarly, any of the endothermic slag-forming components describedpreviously are contemplated for use in these methods. The introducing ofthe endothermic slag-forming component enhances slag formation duringcombustion of the gas generant composition by at least 50%, as measuredby reduced tank wash values. In certain variations, such methodsdesirably enhance slag formation by at least 55%, optionally by at least60%, optionally by at least 63%, optionally by at least 64%, optionallyby at least 65%, optionally by at least 70%, optionally by at least 75%,optionally by at least 78%, optionally by at least 80%, optionally by atleast 85%, and in certain variations, optionally by at least 87%.

In certain aspects, the gas generant composition to which theendothermic slag-forming component is added has a maximum flametemperature at combustion (T_(c)) of less than or equal to about 1,900K(1,627° C.), where the fuel is selected from the group consisting of:guanidine nitrate, copper bis guanylurea dinitrate, hexamine cobalt(III) nitrate, copper diammine bitetrazole, and combinations thereof.The endothermic slag-forming component may be selected from the groupconsisting of: aluminum hydroxide, hydromagnesite, Dawsonite, magnesiumhydroxide, magnesium carbonate subhydrate, Bohemite, calcium hydroxide,and combinations thereof. In certain variations, the maximum flametemperature at combustion (T_(c)) of the gas generant is greater than orequal to about 1,350K (1,077° C.) to less than or equal to about 1,450K(1,177° C.).

In certain preferred variations, the endothermic slag-forming componentintroduced to the gas generant, which enhances slag formation, comprisesaluminum hydroxide and is present at greater than or equal to about 5%by weight to less than or equal to about 20% by weight of a total gasgenerant composition. Thus, introducing a large particle size aluminumhydroxide, for example, with an average particle diameter size ofgreater than or equal to about 150 into a gas generant provides adesirably cool burning gas generant that has superior, enhanced slagformation.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

1. A method of enhancing slag formation for a cool burning gas generantcomposition, the method comprising: introducing an endothermicslag-forming component comprising aluminum hydroxide having particleswith a particle size diameter of greater than 300 μm to a cool burninggas generant composition comprising a fuel and an oxidizer comprisingbasic copper nitrate and having a maximum flame temperature atcombustion (T_(c)) of less than or equal to about 1,900K (1,627° C.),wherein the introducing of the endothermic slag-forming componentenhances slag formation during combustion of the cool burning gasgenerant composition by at least 50% by forming a slag comprisingaluminum oxide particles coated with a copper matrix.
 2. The method ofclaim 1, wherein the fuel is selected from the group consisting of:guanidine nitrate, copper bis guanylurea dinitrate, hexamine cobalt(III) nitrate, copper diammine bitetrazole, and combinations thereof. 3.The method of claim 1, wherein the endothermic slag-forming component ispresent at greater than or equal to about 5% by weight to less than orequal to about 20% by weight of the total cool burning gas generantcomposition.
 4. The method of claim 1, wherein the introducing of theendothermic slag-forming component enhances slag formation duringcombustion of the cool burning gas generant composition by at least 60%.5. The method of claim 1, wherein the fuel is present at greater than orequal to about 25% to less than or equal to about 70% by weight of thetotal cool burning gas generant composition; the oxidizer is present atgreater than or equal to about 25% to less than or equal to about 75% byweight of the total cool burning gas generant composition; theendothermic slag-forming component is present at greater than or equalto about 5% to less than or equal to about 20% by weight of the totalcool burning gas generant composition; and greater than or equal to 0%to less than or equal to about 4% of one or more gas generant additivesselected from the group consisting of: flow aids, press aids, metaloxides, and combinations thereof.
 6. The method of claim 5, furthercomprising a co-oxidizer comprising a perchlorate-based compoundselected from a group consisting of ammonium perchlorate, sodiumperchlorate, potassium perchlorate, lithium perchlorate, magnesiumperchlorate and combinations thereof, present at greater than 0% to lessthan or equal to about 3% by weight of the total cool burning gasgenerant composition.
 7. The method of claim 5, wherein the cool burninggas generant composition consists essentially of: the fuel selected fromthe group consisting of: guanidine nitrate, copper bis guanylureadinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole,and combinations thereof; the oxidizer comprising basic copper nitrate;the endothermic slag-forming component comprising aluminum hydroxide; anoptional co-oxidizer comprising a perchlorate-based compound; and anoptional additive selected from the group consisting of: flow aids,press aids, metal oxides, and combinations thereof.
 8. The method ofclaim 1, wherein the cool burning gas generant composition consistsessentially of the fuel comprising guanidine nitrate present at greaterthan or equal to about 25% to less than or equal to about 70% by weightof the total cool burning gas generant composition; the oxidizercomprising basic copper nitrate present at greater than or equal toabout 25% to less than or equal to about 75% by weight of the total coolburning gas generant composition; the endothermic slag-forming componentcomprising aluminum hydroxide present at greater than or equal to about5% to less than or equal to about 20% by weight of the total coolburning gas generant composition; a co-oxidizer present at greater thanor equal to 0% to less than or equal to about 3% by weight of the totalcool burning gas generant composition; and one or more gas generantadditives present at greater than or equal to 0% to less than or equalto about 4%.
 9. A method of enhancing slag formation for a gas generantcomposition, the method comprising: forming a slag by combusting a coolburning gas generant composition having a maximum flame temperature atcombustion (T_(c)) of less than or equal to about 1,500K (1,227° C.) andcomprising a fuel, an oxidizer comprising basic copper nitrate, and anendothermic slag-forming component comprising aluminum hydroxide havingan average particle size diameter of greater than or equal to about 200μm, wherein the slag comprises aluminum oxide particles coated with acopper matrix.
 10. The method of claim 9, wherein the combusting occursin an air bag inflator of a vehicle and the combusting further compriseselectrically igniting a squib when rapid deceleration or a collision ofthe vehicle is sensed; and burning the squib to ignite the cool burninggas generant composition to generate gases passing through a filter andinflating an airbag of the air bag inflator.
 11. The method of claim 10,further comprising retaining particulates generated during thecombusting of the cool burning gas generant composition as the slag inthe filter, wherein a presence of the endothermic slag-forming componentcomprising aluminum hydroxide having the average particle size diameterof greater than or equal to about 200 μm enhances formation of the slagduring combustion of the gas generant composition by at least 70% ascompared to an amount of comparative particulates formed by combusting acomparative cool burning gas generant having an endothermic slag-formingcomponent comprising aluminum hydroxide having an average particle sizediameter of greater than or equal to about 150 μm.
 12. The method ofclaim 9, wherein the endothermic slag-forming component comprisingaluminum hydroxide is present at greater than or equal to about 5% byweight to less than or equal to about 20% by weight of the total coolburning gas generant composition and the oxidizer comprising basiccopper nitrate is present at greater than or equal to about 30% to lessthan or equal to about 70% by weight of the gas generant composition.13. The method of claim 9, wherein the endothermic slag-formingcomponent comprising aluminum hydroxide having particles with a particlesize diameter of greater than 300 μm.
 14. The method of claim 9, whereinthe endothermic slag-forming component comprising aluminum hydroxide hasa particle size distribution with 90% values of greater than or equal toabout 200 μm to less than or equal to about 300 μm.
 15. The method ofclaim 9, wherein the fuel is selected from the group consisting of:guanidine nitrate, copper bis guanylurea dinitrate, hexamine cobalt(III) nitrate, copper diammine bitetrazole, and combinations thereof andthe fuel is present at greater than or equal to about 25% to less thanor equal to about 70% by weight of the total cool burning gas generantcomposition; the oxidizer is present at greater than or equal to about25% to less than or equal to about 75% by weight of the total coolburning gas generant composition; the endothermic slag-forming componentis present at greater than or equal to about 5% to less than or equal toabout 20% by weight of the total cool burning gas generant composition;and the cool burning gas generant composition further comprises aco-oxidizer present at greater than or equal to 0% to less than or equalto about 3% by weight of the total cool burning gas generantcomposition; and one or more gas generant additives selected from thegroup consisting of: flow aids, press aids, metal oxides, andcombinations thereof present at greater than or equal to 0% to less thanor equal to about 4% of total cool burning gas generant composition. 16.The method of claim 15, wherein the cool burning gas generantcomposition consists essentially of the fuel present at greater than orequal to about 25% to less than or equal to about 70% by weight of thetotal cool burning gas generant composition; the oxidizer comprisingbasic copper nitrate present at greater than or equal to about 25% toless than or equal to about 75% by weight of the total cool burning gasgenerant composition; the endothermic slag-forming component present atgreater than or equal to about 5% to less than or equal to about 20% byweight of the total cool burning gas generant composition; theco-oxidizer present at greater than or equal to 0% to less than or equalto about 3% by weight of the total cool burning gas generantcomposition; and the one or more gas generant additives present atgreater than or equal to 0% to less than or equal to about 4%.
 17. Themethod of claim 16, wherein the co-oxidizer comprises aperchlorate-based compound selected from a group consisting of ammoniumperchlorate, sodium perchlorate, potassium perchlorate, lithiumperchlorate, magnesium perchlorate and combinations thereof.
 18. Amethod of enhancing slag formation for a gas generant composition, themethod comprising: forming a slag by combusting a cool burning gasgenerant composition having a maximum flame temperature at combustion(T_(c)) of greater than or equal to about 1,350K (1,077° C.) to lessthan or equal to about 1,450K (1,177° C.) and comprising a fuelcomprising guanidine nitrate, an oxidizer comprising basic coppernitrate, and an endothermic slag-forming component comprising aluminumhydroxide having an average particle size diameter of greater than orequal to about 150 μm present at greater than or equal to about 5% byweight to less than or equal to about 20% of the total cool burning gasgenerant composition, wherein the slag comprises aluminum oxideparticles coated with a copper matrix.
 19. The method of claim 18,wherein the endothermic slag-forming component comprising aluminumhydroxide having particles with a particle size diameter of greater than300 μm.
 20. The method of claim 18, wherein the cool burning gasgenerant composition consists essentially of the fuel present at greaterthan or equal to about 25% to less than or equal to about 70% by weightof the total cool burning gas generant composition; the oxidizer presentat greater than or equal to about 25% to less than or equal to about 75%by weight of the total cool burning gas generant composition; theendothermic slag-forming component present at greater than or equal toabout 5% to less than or equal to about 20% by weight of the total coolburning gas generant composition; a co-oxidizer present at greater thanor equal to 0% to less than or equal to about 3% by weight of the totalcool burning gas generant composition, and greater than or equal to 0%to less than or equal to about 4% of one or more gas generant additivesselected from the group consisting of: flow aids, press aids, metaloxides, and combinations thereof.